In the extraction of silver,zinc metal is used as a reducing agent. What is the molecular structure of the zinc complex formed in this reaction?

Identify the correctly matched set from the following:

$NiCl_2\{P(C_2H_5)_2(C_6H_5)\}_2$ exhibits temperature-dependent magnetic behaviour (paramagnetic/diamagnetic). The coordination geometries of $Ni^{2+}$ in the paramagnetic and diamagnetic states are respectively

An aqueous solution of metal ion $M1$ reacts separately with reagents $Q$ and $R$ in excess to give tetrahedral and square planar complexes,respectively. An aqueous solution of another metal ion $M2$ always forms tetrahedral complexes with these reagents. Aqueous solution of $M2$ on reaction with reagent $S$ gives a white precipitate which dissolves in excess of $S$. The reactions are summarized in the scheme given below:
$1.$ $M1$,$Q$ and $R$,respectively are :
$(A)$ $Zn^{2+}, KCN$ and $HCl$
$(B)$ $Ni^{2+}, HCl$ and $KCN$
$(C)$ $Cd^{2+}, KCN$ and $HCl$
$(D)$ $Co^{2+}, HCl$ and $KCN$
$2.$ Reagent $S$ is :
$(A)$ $K_4[Fe(CN)_6]$
$(B)$ $Na_2HPO_4$
$(C)$ $K_2CrO_4$
$(D)$ $KOH$
Give the answer for question $1$ and $2$.

The magnetic moment for two complexes of empirical formula $Ni(NH_3)_4(NO_3)_2 \cdot 2H_2O$ is $0$ and $2.84 \ BM$ respectively. The second complex is not a neutral complex. The correct formula and geometry of the first complex is:

$A$ coordination compound is made of $Co^{3+}$,$NH_3$,and $Cl^{-}$. $A$ $0.1 \ M$ solution of this complex when treated with excess silver nitrate gave no precipitate. The formula of the complex and secondary valency of metal are respectively.